Drying kiln



June, 10, 1924. 1,497,084

A. BIGOT DRYING KILN Filed Oct. 6, 1920 2 Sheets-Sheet 1 A. BIGOT DRYING KILN June 10, 1924.

Filed Oct. 6, 1920 2 Sheets-Sheet 3 3 00 1 mmwww..

Patented .iune 10, 1924.

ALEXANDRE BIGOT, F PARIS, FRANCE.

DRYING KILN.

Application filed October 6, 1920. Serial No. 415,207.

7 '0 all whom it may concern:

Be it known that I, ALEXANDRE Broor,

a citizen of the Republic of France, residing at Paris, Seine, in the Republic of France,

have invented certain new and useful Improvements in Drying Kilns; and I do hereby declare the following to be a full, clear,

. and exact description of the invention, such as will enable others skilled in the art to 10 which it appertains to make and use the same, reference being had to the accompanying drawings, and to letters or figures of reference marked thereon, which form a part of this specification. v

The present invention has for its object to construct a continuous heating apparatus, the external walls of which lose by radiation only an insignificant number of calories and the inner walls of which are kept hot at a 0 constant temperature, at determined points,

by means of heat accumulators placed be tween the two walls. The inner hot walls surround chambers in which are placed, on suitable supports, the substances such 'as clay, gypsum, etc., it is desired to subject to heat. Owing to the nature of the substances which partially constitute them, these apparatus can only be employed at temperatures which are below a dull red heat the same arrangement of walls and accumulators may serve for the construction of cooling chambers.

The external walls are made of or covered with incombustible materials, which are bad conductors of heat, such as light magnesia, the light infusible silicas, etc., in powder or agglomerated, the specific heat and con ductivity of which are very low. The aba0 be very small.

The inner walls are constructed of rigid materlals which are sufficiently conducting,

such as plates of metals or of alloys, partitions and ceilings (floors) of thin armoured sorption and loss of heat by these wallswill passages between each of them. By natural or artificial aspiration or by compression, hot gases are caused to circulate through the inert materials and between the walls. These gases give up the major portion of their heat to the inner wall and to the inert materials which become true accumulators of heat and regulate the emission of the heat towards the chambers. It is therefore advantageous to employ a considerable quantity of inert materials having as great a specific heat as possible.

A similar phenomenon will be produced if cold gases be sent into the accumulators: the inner walls will emit units of cold into the chambers.

Under the action of the hot gases and of the heat transmitted into the chambers, the temperature of these chambers rises, and the materials which they contain are enabled to undergo .a' certain number of physical operations, such as: Drying, in the caseof moist clays, etc.

Dehydration, in the case of gypsum, etc.

Chemical decomposition, in the case of bicarbonate of soda, etc.

Combination, in the case of silico-limestones, and i i The partial loss of water and chemical action as in the bakingof bread.

Openings suitably made in the walls permit of the escape of the gases or vapours, which are produced in the course of the heating, these gases orvapours may be collected if necessary in suitable apparatus.

Other openingsmay be made for the purpose of introdu'cing'into the chambers air or gases which are heated or atthe surroundingtemperature in order to facilitate evaporation, or for raising the temperature, orfor producing physical or chemical reactions.

The apparatus which forms the subject matter of the present invention may be constructed indifferent forms, and the applicant indicates below certain of them without this enunciation being limitative:

- Stoves or driers on fixed supports or revolving platforms, etc.

Shaft furnaces with one or more chainbers, etc.

Whatever be the form of these apparatus, they can be heated by meansgoffany kind of grate whatever or by utilizing heat lost by the grates, furnaces, etc.

Of the various types which can be constructed, according to this invention, the ap v plicant will proceed to describe, by way of example, and with reference to the accompanying drawings:

Figure 1 is a vertical section of a shaft furnace embodying another form of the inforinof the shaft furnace.

This furnace :may be of circular or polygonal-form (see Figs. 1 and 2) is specially devised for the calcining of gypsum and is constructed in the following manner An inner vertical chamber C, C G has its walls V of-reinforced concrete,,as thin as possibleanld covered internally with a coating of. cement which withstands wear caused by the introduction into this lining of abrasive substances. This inner chamber is pierced withopenings d, (l the function of which will be hereinafter described. The part .0 serves for theeharging in of the crude gypsum. The part C is provided at the end with two grinding cylinders .c which act as conveyors rotating in the direction of the arrows and the distance between the axles of which is adjustable at will.

Atthe outside ofthe furnace are ar-ranged pillars of reinforced concrete 7 resting at their base on a foundation of reinforced concrete and connected to each other by external beams or horizontal ties b.

The walls of the inner chamber are connected together by ceiling h, M, 7& of reinforced concrete to the whole of the construction of reinforced concrete which forms a monolith. Walls M of insulating materials form the outer walls of the furnace. These walls are covered outwardly with a coating of cement or armoured cement 2'. Furthermore, insulating materials M M cover the ceiling 7L 7L and theupper part C of the walls V.

The hot gases enter by the passage A into a chamber E. This chamber communicates with the interior of the chamber C through a suitable number of openings 0!. The arches 7c of this chamber are pierced with numerous openings, likewise the ceiling h.

The spaces included between the wallsV, M-the brick arches and the ceilings h, it constitute galleries which are filled with inert materials forming accumulators. These galleries communicate with the chambers E by openingsin the arches k, with the chamber C through the openings d, and with the outside through the opening L made in the upper ceiling 72, and which can be regulated at will by means of a damper.

An upper platform Q placed at the level the part C up to the first openings 03, by

means of the charging doors 6 (see Figures 1 and 3), made 111 the outer wall of the fur- .nace and in the wall V. After having closed these doors, the hot gases are admitted by the passage A and the furnace is filled little by little by means of the elevator which delivers the gypsum. in pieces through the opening 6 in the chamber C.

The hot gases enter for the greater part into the accumulators G and a portion passing through the openings v(land through the material where they give up the greatest portion of their heat and their temperature is lowered. The gases contained in the accumulators are drawn through the opening L by means of a fan Z whichcauses them to enter throughthe openings al in the chamber C where they conclude by giving up their heat to the column of gypsum contained in the said part G The upward movement of thegases .in 0 produces in thechamber .C a-suction which determines theentrance of the hot gases into this chamber throughthe openings (i. The mass of gypsum therein issubiected to heating both by radiation and conductivity, and to direct heating by a fractionof the hot gases.

The movement of the cylinders .6 regulates the discharge of the plaster which falls crushed into trucks W, or on to a conveyor belt.

The suction produced towards the top of the chamber C causes a certain quantity of by means of openings dwvhich are made in in the walls of the central chamber 0. An elevator 02 delivers the -materials to be treated into a hopper R, on to a trap a which closes the chamber '6 at its upper part. It can rock on a shaft a by an auto matic mechanism setinaction-from time to time by a special operating device on the elevator. shown in Figure 3.

The shaft furnace may, itmust lee-under- This well known device is not.

stood be provided with apparatus for controlling pressure, temperature, etc.

What I claim and desire to secure by Letters Patent of the United States is 1. In apparatus for heating, a central heating chamber having highly conducting Walls, outer Walls spaced therefrom of insulating material, heat accumulating material included between said Walls co-extensive with said chamber, means to supply hot gases to said heat-accumulating material, and means to vent a portion of said gases from said accumulating material to said chamber at different points along its length.

2. In apparatus for heating, a vertical, central heating chamber, heat accumulators surrounding said chamber, means to supply hot gases to said accumulators, means to vent a portion of said gases from the accumulators to said chamber at diflferent points along its length, means to continuously discharge said chamber at one end and means to continuously charge said chamber at the other end.

3. In apparatus for heating, a vertical, central heating chamber having highly conducting Walls, heat accumulators surrounding said chamber throughout its length, a charging means for said chamber, means for continuously discharging said chamber, means to supply hot gas to said accumulators, means to vent gas from the accumulators to said chamber at different points along its length and means to discharge gas from the end of the accumulators to said charging means and there mix With gases emanating from said chamber.

In testimony whereof I have signed this specification in the presence of a subscribing Witness.

ALEXANDBE BIGOT. Witness:

CLEMENT S. EDWARDS. 

